Hakuin joined the Rinzai Zen sect about 1700. He subsequently became an itinerant monk, during which time he first experienced enlightenment, and returned in 1716 to the Shōin Temple in his native Hara, which remained his base until his death.

Buddhism in Japan had been largely coopted by the Tokugawa shogunate (the ruling feudal government), but while many priests sought personal advancement, Hakuin lived in great poverty among his peasant parishioners. His spirituality, contentment, and humility attracted a large following that became a new foundation for Rinzai Zen in Japan.

Hakuin taught that direct knowledge of the truth is available to all, even the lowliest, and that a moral life must accompany religious practice. He utilized koans (unsolvable riddles) to aid meditation and invented the well-known paradox of contemplating the sound of one hand clapping. His chief writings are Keisō dokozui (“Poisonous Stamens and Pistils of Thorns”), intended for advanced students of Zen; Hogo-roku (“Record of Talks on the Law”), doctrines that “accommodate” Zen principles to local conditions; and Orategama (The Embossed Tea Kettle) and Yasen kanwa (“A Chat on a Boat in the Evening”), two works of practical advice.

Hakuin also is known as an artist and calligrapher. Typically using bold brushstrokes and dark ink colours, he sought to evoke in the viewer’s mind his feelings on Zen practice and on the attainment of enlightenment.